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71.
Sessler JL Maeda H Mizuno T Lynch VM Furuta H 《Chemical communications (Cambridge, England)》2002,(8):862-863
Novel quinoxaline derivatives bearing dipyrromethane or tripyrromethane substituents act as improved anion receptors as compared to the unsubstituted dipyrrolylquinoxaline core from which they are derived. 相似文献
72.
Ohki Y Matsuura N Marumoto T Kawaguchi H Tatsumi K 《Journal of the American Chemical Society》2003,125(26):7978-7988
A series of sulfido-bridged tungsten-ruthenium dinuclear complexes Cp*W(mu-S)(3)RuX(PPh(3))(2) (4a; X = Cl, 4b; X = H), Cp*W(O)(mu-S)(2)RuX(PPh(3))(2) (5a; X = Cl, 5b; X = H), and Cp*W(NPh)(mu-S)(2)RuX(PPh(3))(2) (6a; X = Cl, 6b; X = H) have been synthesized by the reactions of (PPh(4))[Cp*W(S)(3)] (1), (PPh(4))[Cp*W(O)(S)(2)] (2), and (PPh(4))[Cp*W(NPh)(S)(2)] (3), with RuClX(PPh(3))(3) (X = Cl, H). The heterolytic cleavage of H(2) was found to proceed at room temperature upon treating 5a and 6a with NaBAr(F)(4) (Ar(F) = 3, 5-C(6)H(3)(CF(3))(2)) under atmospheric pressure of H(2), which gave rise to [Cp*W(OH)(mu-S)(2)RuH(PPh(3))(2)](BAr(F)(4)) (7a) and [Cp*W(NHPh)(mu-S)(2)RuH(PPh(3))(2)](BAr(F)(4)) (8), respectively. When Cp*W(O)(mu-S)(2)Ru(PPh(3))(2)H (5b) was treated with a Br?nstead acid, [H(OEt(2))(2)](BAr(F)(4)) or HOTf, protonation occurred exclusively at the terminal oxide to give [Cp*W(OH)(mu-S)(2)RuH(PPh(3))(2)](X) (7a; X = BAr(F)(4), 7b; X = OTf), while the hydride remained intact. The analogous reaction of Cp+W(mu-S)(3)Ru(PPh(3))(2)H (4b) led to immediate evolution of H(2). Selective deprotonation of the hydroxyl group of 7a or 7b was induced by NEt(3) and 4b, generating Cp*W(O)(mu-S)(2)Ru(PPh(3))(2)H (5b). Evolution of H(2) was also observed for the reactions of 7a or 7b with CH(3)CN to give [Cp*W(O)(mu-S)(2)Ru(CH(3)CN)(PPh(3))(2)](X) (11a; X = BAr(F)(4), 11b; X = OTf). We examined the H/D exchange reactions of 4b, 5b, and 7a with D(2) and CH(3)OD, and found that facile H/D scrambling over the W-OH and Ru-H sites occurred for 7a. Based on these experimental results, the mechanism of the heterolytic H(2) activation and the reverse H(2) evolution reactions are discussed. 相似文献
73.
Mengfei Wang Dr. Kei Murata Prof. Kazuyuki Ishii 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(35):8994-9002
Mono- and di-nuclear tricarbonyl Re(I) tetraazaporphyrin complexes ( Re1TAP and Re2TAP ) are investigated and compared with Re(I) phthalocyanine complexes ( Re1Pc and Re2Pc ). Although Re2Pc is unstable in polar solvents, and easily undergoes demetallation reaction, the coordination of the TAP ligand significantly improves the tolerance toward polar solvents, affording more stability to Re2TAP . Additionally, the incorporation of [Re(CO)3]+ unit(s) and the TAP ligand results in remarkable positive shifts in both oxidation and reduction potentials. Consequently, the more positive oxidation potentials of the ReTAP complexes significantly increase the tolerance toward oxidation, while the reduction potential indicates that Re2TAP is suitable for a soluble electron acceptor. In contrast to Re1Pc and Re2Pc , Re1TAP and Re2TAP show unique broad Q bands, which can be attributed to the admixture of the π-π* and metal-to-ligand charge transfer characters, owing to the lowered π orbital energy in the TAP complexes. This study is useful for controlling electronic properties and realizing high stability in Pc analogues. 相似文献
74.
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75.
Uric acid quantification in fingernail of gout patients and healthy volunteers using HPLC‐UV
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Wenlong Jin Gao Li Kenichiro Todoroki Hajime Mizuno Toshimasa Toyo'oka Jun Zhe Min 《Biomedical chromatography : BMC》2016,30(8):1338-1342
The presence of elevated uric acid (UA) levels is a sign of gout, that is, hyperuricemia. In this study the monitoring of the UA levels in less‐invasive biological samples, such as the human fingernail, is suggested for the diagnosis and therapy of gout. Twenty‐six healthy volunteers (HV) and 22 gout patients (GP) were studied. The UA was extracted from human fingernail samples, then separated on an Inertsil ODS‐3 column (250 × 4.6 mm i.d., 4.0 μm, GL Sciences) by isocratic elution using methanol–74 mm phosphate buffer (pH 2.2) 2:98 (v/v). A UV detector was used to monitor the samples at 284 nm. Using the developed method, different UA concentrations were found in the GP and HV. When comparing the concentrations from GP with those from HV, a statistically significant correlation was observed between the UA (p < 0.01). In this study, the UA was confirmed as a potential biomarker for the diagnosis and therapy of gout. We have developed a novel sensitive, and simple method for the determination of UA in the fingernails of GP and HV. The human fingernail may serve as a noninvasive biosample for the diagnosis of gout. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
76.
Shinji Ejiri Sinya Aoki Tetsuo Hatsuda Kazuyuki Kanaya Yoshiyuki Nakagawa Hiroshi Ohno Hana Saito Takashi Umeda 《Central European Journal of Physics》2012,10(6):1322-1325
We study the QCD phase structure at high temperature and density adopting a histogram method. Because the quark determinant is complex at finite density, the Monte-Carlo method cannot be applied directly. We use a reweighting method and try to solve the problems which arise in the reweighting method, i.e. the sign problem and the overlap problem. We discuss the chemical potential dependence of the probability distribution function in the heavy quark mass region and examine the applicability of the approach in the light quark region. 相似文献
77.
78.
Wei Sun Xiaojie Li Kazuyuki Hokamoto 《Applied Physics A: Materials Science & Processing》2014,117(4):1941-1946
We show direct evidence that underwater shock wave enables us to bond multithin plates with flat, parallel, and high-strength interfaces, which are key requirements for functionally graded material (also called graded density impactor). This phenomenon is ascribed to the super short duration of the high-speed underwater shock wave, reducing the surface tension, diffusion, evaporation, deposition, and viscous flow of matter. Thin magnesium, aluminum, titanium, copper, and molybdenum foils were welded together and designed with the increase in density. Experimental evidence and numerical simulation show that well bonding between the multilayer structures. Microstructure examinations reveal that the dominant interfacial form shifts from waviness to linearity. Graded density impactor with multilayer structure is proved that can produce quasi-isentropic compression in two-stage gas gun experiment with a designed pressure loading profile, which suggests a feasible method to simulate the conditions we want to study that were previously inaccessible in a precisely controlled laboratory environment. 相似文献
79.
Proton Order–Disorder Phenomena in a Hydrogen‐Bonded Rhodium–η5‐Semiquinone Complex: A Possible Dielectric Response Mechanism
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Dr. Minoru Mitsumi Kazunari Ezaki Yuuki Komatsu Prof. Dr. Koshiro Toriumi Dr. Tatsuya Miyatou Prof. Dr. Motohiro Mizuno Nobuaki Azuma Prof. Dr. Yuji Miyazaki Prof. Dr. Motohiro Nakano Prof. Dr. Yasutaka Kitagawa Dr. Takayasu Hanashima Dr. Ryoji Kiyanagi Dr. Takashi Ohhara Prof. Dr. Kazuhiro Nakasuji 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(27):9682-9696
A newly synthesized one‐dimensional (1D) hydrogen‐bonded (H‐bonded) rhodium(II)–η5‐semiquinone complex, [Cp*Rh(η5‐p‐HSQ‐Me4)]PF6 ([ 1 ]PF6; Cp*=1,2,3,4,5‐pentamethylcyclopentadienyl; HSQ=semiquinone) exhibits a paraelectric–antiferroelectric second‐order phase transition at 237.1 K. Neutron and X‐ray crystal structure analyses reveal that the H‐bonded proton is disordered over two sites in the room‐temperature (RT) phase. The phase transition would arise from this proton disorder together with rotation or libration of the Cp* ring and PF6? ion. The relative permittivity εb′ along the H‐bonded chains reaches relatively high values (ca., 130) in the RT phase. The temperature dependence of 13C CP/MAS NMR spectra demonstrates that the proton is dynamically disordered in the RT phase and that the proton exchange has already occurred in the low‐temperature (LT) phase. Rate constants for the proton exchange are estimated to be 10?4–10?6 s in the temperature range of 240–270 K. DFT calculations predict that the protonation/deprotonation of [ 1 ]+ leads to interesting hapticity changes of the semiquinone ligand accompanied by reduction/oxidation by the π‐bonded rhodium fragment, producing the stable η6‐hydroquinone complex, [Cp*Rh3+(η6‐p‐H2Q‐Me4)]2+ ([ 2 ]2+), and η4‐benzoquinone complex, [Cp*Rh+(η4‐p‐BQ‐Me4)] ([ 3 ]), respectively. Possible mechanisms leading to the dielectric response are discussed on the basis of the migration of the protonic solitons comprising of [ 2 ]2+ and [ 3 ], which would be generated in the H‐bonded chain. 相似文献
80.